High speed printer



July 21,1959 F. M. DEMER Em 2,895,411

HIGH SPEED PRINTER V IN V EN'TORS FRED ERICK M. E I BY RIQHARD H. HA N T N Flax WawM ATTORNEYS July 21, 1959' F. M. DEMER EIAL HIGH SPEED PRINTER 5 Sheets-Sheet 2 Filed Dec. 2'7, 1956 /6 v INVENTORS FREDERICK M. DEMER a RICHARD H. HARRINGTON their ATTORNEYS July 21, 1959" F. M. DEMER HAL 2,895,411

HIGH SPEED RRINTER Filed Dec. 27, 1956 3 Sheets-Sheet 3 5/ f7 ff A 2' z;

INVENTORS FREDERICK M. DEMER 8| RICHARD HARRINGTON "18W ATTORNEYS United St tes P t HIGH SPEED PRINTER Frederick M. Demer, Johnson City, and Richard H. Harrington, Vestal, N.Y., assignors to International Business Machines Corporation, New York, N .Y., a corporation of New York Application December 27, 1956, Serial No. 630,817

6 Claims. (Cl. 101-93) Thisinvention relates to a high speed printer and, more particularly, to such printers in which a number of the printing elements are in continuous motion.

The translation of computed information from electrical signals to printed characters has been one factor limiting computer speeds. Among the proposed high speed printers, those having continuously moving printing elements, often termed on-the-fly printers, have many advantages. For example, continuously rotating type wheels or drums may cooperate with selectively actuated hammers to provide rapid printing, a number of these hammers ordinarily being laterally disposed to print lines of characters. It is apparent that the several printing hammers, one for each column, must be closely synchronized in their actuation to preclude faulty alignment of the printed characters.

Previous printing arrangements have included solenoid hammer actuators. However, electrical timing variations due to changes in supply voltages and other factors have resulted in objectionable misalignment of the printed lines.

Accordingly, it is an object of the present invention to provide a high speed printer in which the printed characters are accurately aligned.

It is another object of the invention to provide a printer of the above character in which continuously moving character carrying members are synchronized with actuating hammers to provide accurately printed lines.

'It is a further object of the invention to provide a printer having the above characteristics in which moving hammers synchronized with the type carrying member are selectively unlatched to enable the selected hammer to actuate printing mechanism. 2

These and further objects of the invention are accomplished by disposing a firing pin adjacent to a continuously moving type wheel. A plurality of hammers rotated in synchronism with the type wheel are normally held out of engagement with the pin. Upon reception of a printing impulse, one of the continuously rotating hammers drives the firing pin against a selected character on the type wheel.

In one embodiment of the invention, a series of hammers and associated latches are carried by a rotor synchronized with the type wheel, a hammer being selectively unlatched in response to a printing impulse. Preferably two rotors are provided so that the speed of rotation of the hammers may be halved.

These and further objects and advantages of the present invention will be more readily understood when the following description is read in connection with the accompanying drawings, in which:

Figure 1 is an elevation, partially broken away, of one printing station of a high speed printer embodying the principles of the present invention;

Figure 2 is a plan view of a plurality of the printing stations illustrated in. Figure 1 showing the synchronized drive means between various elements in the system;

Figure 3 is a view in perspective, greatly enlarged, illustrating a hammer and latch of Figure 1 in detail;

2,895,41l Patented July 21, 1959 Figure 4 is a view in perspective, greatly enlarged, of an interposer element used in the printer; and

Figures 5A to 513. are fragmentary views of the printer showing the relative position of essential elements at five progressive times in an individual printing operation according to the invention.

Referring to a typical embodiment of the invention in greater detail with particular reference to Figures 1 and 2, suitable supporting structure for a high speed printer includes outer frame members 9 between which are disposed type wheels 10, each carrying a complete array of forty-eight characters 11, rotated by a shaft 12 journaled in the members 9. A pulley 13 on one end of the shaft 12 is driven by a belt 14 looped around. a drive pulley 15 on a driving motor 16.

Pulleys 17 and 18 guide inked ribbon 19 and cooperating pairs of drive rolls 20-21 and 2223 control the movement of a continuous paper sheet 24 in front of the type wheels 10. Any conventional ribbon and paper drive may be substituted for this arrangement.

, A firing pin 25 at each of the printing stations includes an enlarged head portion 26 forming a shoulder 27 normally engaging a bushing or guide 28 formed of nylon, for example, in a support 29 formed with camming sur faces 29a and 2922. A further bushing 30, also formed of nylon, is positioned at the other end of the support 29 to guide the pin 25 toward the type wheel 10. A spring wire 31 anchored in a flange 32 on the member 30 extends through an opening 26a in the firing pin head 26 to urge it rearwardly toward the bushing 28.

A pair of rotors 33 and 34 are formed by parallel mounted discs 35 and 36 respectively carried by shafts 37 and 38. The periphery of the discs 35 and 36 include knock off cams35a and 36a. A gear 39 (Figure 2) afixed to the shaft 12 drives through an idler gear 40 on a shaft 41 a lower rotor gear 42 mounted on the shaft 37. Another gear on the shaft 38 (not shown) meshes with the rotor gear 42 to drive the rotor 34 in a direction opposite to the rotor 33. In the particular embodiment of the invention being described, a four to one speed ratio is established between the rotors 33 and 34 and the type wheels 10.

Six equally spaced pivot pins 43 extend through the discs 35 on the rotor 33, each pin carrying a hammer 44 and a latch 45, best shown in Figure 3. Each of the hammers 44 is formed by a thick striking portion 46 from which extends a hook 47. A thinner portion 48 one half the thickness of the outer striking portion includes an opening permitting the hammer 44 to swing freely on the pin 43.

The latch 45 is formed by an arm 49 from which extends a stop 50 and a tail section 51, the outer latch sections having the same thickness as the outer portion of the hammer 44. The inner section of the latch includes an opening fitting the pins 43 and is one half the outer thickness to permit its cooperation with the hammer 44 in. a manner to be explained in detail hereinafter.

In order to unlatch each hammer 44 from. its retracted position, an interposer 52 (Figure 4) at each printing station consists of a bar specially formed at one end with outer rounded edges 53 and an inner flattened and recessed section 54. An armature 55 (Figure 1) carrying the interposer 52 is selectively actuated by a magnet 56 about a pivot 57, a spring 58 biasing the assembly against a stop 59. The interposers 52 at adjacent printing stations are preferably displaced circumferentially from each other to provide the width of two columns for each magnet and armature.

In the typical embodiment of the invention described herein, the type wheels 10 carry forty-eight characters 11 and the rotors 33 and 34 rotate at four times the speed of the wheel 10. Therefore, in order to print a series of lines at a 600 line per minute rate, for example, each of the forty-eight possible printing times during one cycle point may be allocated a period of 1.75 milliseconds, the time for printing one line being 84 milliseconds. Adding an additional 16 milliseconds for line spacing provides a total time of 100 milliseconds per line. Acceptable alignment of characters on the paper is plus or minus .005 inch. Therefore, the action of the firing pin 25 must be within 40 microseconds of the theoretically proper time.

In operation, it will be apparent that the twelve actuating hammers 44, six on each rotor, are carried past the firing pin 25 forty-eight times during each revolution of the type wheel 10, once for each possible character. The rotors 33 and 34 are displaced from one another by 30 degrees so that the hammers on the rotor 33 alternate with those on the rotor 34 in passing the firing pin 25. Therefore, in order to print a particular character at one or more of the printing stations, selected magnets 56 receive a printing impulse which results in the interposer 52 being displaced into the position illustrated in Figure A. An instant later, the inner flattened section 54 of the interposer 52 engages the outer thick hammer portion 46, as shown in Figure 5B, causing clockwise rotation of the hammer 44.

To reduce wear on the latching surfaces, the camming surface 29a is formed by an are about a center slightly removed from the rotor center. The outer portions 46 of latched hammers 44 engage the surface 29a smoothly at the guide 30 and subsequently are cammed slightly clockwise to remove the load from the latching surfaces of all hammers. Consequently, the interposer 52 may function without wearing the latching surfaces. The surface 29a merges with a true are about the rotor center at a point 290.

As will be evident from Figure 3, a leading edge 48a on the hammer inner section 48 engages an edge 51a of the latch tail section 51 resulting in clockwise rotation of this member. Accordingly, the latch arm 49 releases the hook 47 on the next hammer 44 (Figure 5B) and under the influence of centrifugal force generated by rotation ofthe rotor 33, this hammer swings outwardly as illustrated in Figure 50.

It should be noted that while the interposer 52 causes clockwise rotation of one of the hammers 44 and its associated latch 45, the latch tail section 51 engages the shaft 37 (Figure SE) to limit such clockwise rotation. Subsequently centrifugal force urges the latch 45 to rotate in a counterclockwise direction due to the heavy tail section 51, such rotation being limited by engagement of this section with the following hammer and latch, as shown in Figure 5D.

Positive removal of the interposer 5 2 from the path of any succeeding hammers 44 is provided by a camrning action between the immediately succeeding knock off cams 35a and-the outer rounded'edges 53 on the end of the interposer 52 (Figure 4). i r I The hammer 44 released by the interposer 52 swings outwardly under the influence of centrifugal force until the striking section 46 engages the latch stop 50 (Figure 5D). The hammer 44 is held against the stop 50 by.

centrifugalforce so that it may strike the firing pin from a stableprecisely reproducible position. As shown in Figure 5D, upon reaching the top of its arc the hammerc44 strikes the end of the firing pin 25,

the mass of the pin closely approximating the effective massof the hammer. Accordingly, the kinetic energy of the hammer 44. is transferred by impactto the pin 25 which moves, forward at a high. velocity carrying with it the paper 24, and ribbon19 against a selected one of the characters 11 on the type wheel 1.0 (Figure 5E). The firlng. 25 then rebounds from. the wheel 10. but; is effectively restrained from further action by the spring 31.

Thestriking section 46 of the hammer 44; loses; all

forward velocity at the instant of impact. Thereafter, the hammer rotates smoothly back toward its latched position as the pivot pin 43 pulls it into contact with the edge of the guide 30, the hammer 44 finally resuming its normal and stable latched position under the influence of centrifugal force.

It will be apparent that the cooperation of the upper rotor 34 with its associated interposer is exactly the same as that discussed in connection with the rotor 33.

The precision with which printing may be accomplished with the above described embodiment of the present invention will be evident when it is understood that the 60 degree interval between hammers on one of the rotors represents 3.5 milliseconds of time, assuming rotation at a speed of 2800 revolutions per minute. One degree variation, therefore, produces less than 60 microseconds variation in hammer blow timing. Moreover, mechanical synchronization of the two rotors 33 and 34 with the type wheel 10 may be very closely controlled with commercially available precision gears to achieve these results.

It will be understood that the above described embodiment of the invention is illustrative only and modifications thereof will occur to those skilled in the art. T herefore, the invention is not to be limited to the particular apparatus described herein but is to be defined by the appended claims.

Weclairn:

1. In a high speed printer, means carrying a plurality of characters past a printing position, a firing pin adjacent to the printing position adapted to urge data receiving means against the characters, a rotating element synchronized with the character carrying means, a plurality of hammers pivoted on the rotating element, the effective mass of each hammer approximating the mass of the firing pin, and means selectively enabling.

one of said hammers to strike the firing pin and print a selected character on the data receiving means.

2, In a high speed printer, means carrying a plurality of characters past a printing position, a firing pin adjacent to the printing position adapted to urge data receiving means against the characters, a rotating element synchronized with the character carrying means, a plurality of hammers pivoted, on the rotating element, the effective mass of each hammer approximating the mass of the firing pin, and means to condition a selected one. of the hammers to strike the firing pin and print a.

selected character on the data receiving means.

3. In a high speed printer, a member rotating a plurality of characters along an annular path, a firing pin adjacent to the annular path and adapted to urge data. receiving means against the characters, a rotating element synchronized with the member, a plurality of hlammers pivoted on the rotating element, the effective mass of each hammer approximating the mass of the firing pin, latch means normally holding said hammers in a retracted position against centrifugal force acting thereon, and means to disengage a selected hammer from the latch means to enable it to be pivoted outwardly by centrifugal force to strike the firing pin and print a selected character on the-data receiving means.

4, In a high. speed printer, a rotating wheel having a plurality of characters spaced along its periphery, a firing pin positioned adjacent to the wheel and adapted to urge data receiving means against the characters, a rotating element synchronized with the wheel, a plurality of hammers pivoted on the rotating element, the effective mass a plurality-of charactersspaced along its,v periphery, a.

firing pin positioned radially of the wheel and adapted to urge data receiving means against the characters, a rotating element synchronized with the wheel, a plurality of hammers pivoted on the rotating element and urged outwardly by centrifugal force, a like plurality of latches pivoted concentrically with the hammers to hold them in retracted position against centrifugal force, an interposer positioned adjacent to the rotating element, and means to urge the interposer into engagement with one of the hammer and latch combinations to unlatch a selected hammer and enable it to be pivoted outwardly by centrifugal force to strike the firing pin and print a selected character on the data receiving means.

6. Apparatus as defined in claim 5 in which a cam- 6 ming surface is provided adjacent to the rotating ele ment to engage the hammer and latch combinations and relieve the load on latching surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 1,896,538 Bryce Feb. 7, 1933 1,981,990 Carroll Nov. 27, 1934 2,013,533 Buhler Sept. 3, 1935 2,053,063 Bryce Sept. 1, 1936 2,627,807 Buhler Feb. 10, 1953 2,766,686 Fo-menlco Oct. 16, 1956 2,787,210 Shepard Apr. 2, 1957 

